Telephone-exchange system.



L. H. JOHNSON.

TELEPHONE EXCHANGE SYSTEM.

APPUCATION FILED MAY 25. 1917.

Patented Feb. 19, 19180 is possible v Whether the subscriber nnrrnn s rars are nine.

LEWIS H. JOHNSON, OF BLOOMFIELD, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF

NEW YORK, N. Y. A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Feb. 19, 1918.

Application filed May 25, 1917. Serial No. 170,859.

To all whom it may concern:

Be it known that I, LEWIS H. JOHNSON, a citizen of the United States, residing at Bloomfield, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems, and more particularly to such systems in which both common battery and magneto or local battery lines terminate at a central oltice at which there are connecting circuits for establishing connections between such lines.

The object of this invention is to provide improved signaling means for systems of this character.

In accordance with a feature of this invention, an operating circuit is completed for a signaling device when the subscriber of theconnected line, whether magneto or common battery, rings oii or restores the receiver to the switchhook, thereby causing a signaling device associated with a universal connecting circuit to furnish a signal of one indication. The same signaling device, upon the subsequent removal of the receiver from the switchhook by the subscriber 01" a connected common battery line, is intermittently operated to furnish a signal of another indication, thereby enabling the operator to distinguish between disconnect signals and recall signals.

In systems heretofore used in which connections are established with magneto lines as called lines, it is necessary to actuate a ringing key to connect the source of ringing current to the line for operating the call bell. This, the operator does, and then waits a short time before actuating a listening key to connect the operators telephone set therewith to learn whether the called subscriber has responded. If the subscriber has not responded the ringing key must again be operated to again ring the call bell of the wanted line. In these systems now in use, it

that the operator may actuate the ringing key and later, thinking that the called subscriber had not been signaled, may again actuate the ringing key without first actuating the listening key to determine has responded. If

the subscriber has the receiver to his ear when the ringing key is thus again actuated, thesource of ringing current is connected in circuit with the receiver, and, therefore, results in ringing in the subscribers ear, which is very disagreeable. In a system embodying the present invention, by causing the operation of a signaling device when the ringing key is first actuated, which signaling device remains operated until the listening key is subsequently actuated, the operated or non-operated condition of this signaling device serves to keep the operator fully advised as to whether the ringing or listening key was last actuated, so that there is less probability of ringing the subscriber in the ear.

For a more complete understanding of this invention, reference should be had to the following specification, taken in connection with the accompanying drawing in which there is shown a common battery telephone line A, extending from a subscribers station to a central otiice, and a magneto or local battery telephone line B, eXtending from a SubZCribers station to the central ofiice. At the central oflice there is located a cord circuit C of the universal type for interconnecting subscribers lines. This cord circuit may be employed for connecting together two magneto lines or two common battery lines or a magneto and a common battery line. It is believed that the nature of this invention is such that it will be fully un' derstood from the description of the operation of the system disclosed in the drawing; hence, it will be so described.

The subscriber of a line A initiates a call in the usual manner, causing the lighting of the line lamp 5, in response to which the operator inserts answering plug 6 into line jack 7. Relays 8 and 9 and cutoff relay 10 are thereupon operated over a circuit from battery through the winding of relay 8, left-hand winding of relay 9, sleeve contacts of the answering plug 6 and line jack 7, and the winding of cutoff relay 10 to ground. Relay 9 operates when either end of the cord circuit is connected with either a common battery or magneto line. Relay 8, however, is marginal and operates when connected in circuit with the low resistance winding of the cutofl relay of a common battery line, but does not operate when com nected in circuit with the high resistance winding of a cutofi relay of a magneto line.

'Relay 8, in operating, connects battery to the cord circuit, through the windings of supervisory relay 11, which now operates over the line. Upon the actuation of the supervisory relay 11, relay 12 is operated over a circuit from battery through the contact of relay 9, normal contact of listening key 13, winding of relay 12, normal contact of relay 14:, al-

ternate contact of supervisory relay 11, and

answering supervisory lamp 15 to ground. The winding of relay 12 is of high resistance so that the supervisory lamp does not light when in circuit therewith. The operation of relay 12 connects relay 14 in parajllel with the lamp 15, but the relay 14 does not operate while it is shunted by the relatively low resistance lamp 15.

The operator may now actuate the listening key 13, connecting the operators tele phone set with the cord circuit. Upon the actuation of this listeningkey, the normal contact thereof is opened, thereby causing the de'energization of relay 12, which re leases its armatures. The operator, upon being advised that the calling subscriber A desires to be connected with a magneto line, for example, line B, restores the listeningkey to normal position, and inserts calling plug 16 into line jack 17. Relay 18 is marginal, and does not operate when connected in circuit with the high resistance winding of cutoff relay 20 of the magneto line. The restoration of the listening key to normal permits the energization of relay 12 as before. The operator may now cause the operation of the call bell at station B by actuating a ringing key 25. Upon the actuation of the ringing key 25, contact 26 thereof is closed to cause the operation of a relay 27 over a circuit from battery through contact 26 of key and the winding of relay 27 to ground. Relay 27. in operating. establishes a locking circuit for itself from battery through the contact of relay 9, normal contact of listening key 13, and contact and winding of relay 27 to ground. Upon the operation of relay 27, calling supervisory lamp 35 is lighted over a circuit from battery through the contact of relay 9, nor- Inal contact of the listening key 13, concrank of generator 39 astored to normal, and the ringing key again actuated to again operate the call bell at station E. Upon this reactuation of the ringing key 25, relay 27 is .again energized and locked up, and the lamp 35 is lighted. If, when the operator again actuates the listening key, it is found that subscriber B has responded, the ringing key will, of course, not be actuated again.

At the conclusion of the conversation between subscribers A and B, A restores the receiver to the switchhook, causing the deenergization of supervisory relay 11, whereupon answering lamp 15 is intermittently lighted over a circuit from battery through interrupter 38, upper alternate contact of relay 1'2, alternate contact of supervisory relay 11, and lamp 15 to ground, to thereby furnish a disconnect signal. The de'e'nergization of the answering supervisory relay 11 interrupts the shunt about the relay 1%, which now operates and locks up in series with relay 12, the locking being controlled by the listening key ating, connects interrupter 41 to the front contact of answering supervisory relay 11. The subscriber B, in ringing otl', gives the short turn, thereby energizing relay 37, which attracts its armatures. Upon'the energization of relay 37, relay 36 is actuated over a circuit from battery through .the'contact of relay 9, normal contact of listening key 13, winding of relay 36, normal contact of relay 40, alternate contact of relay 37, and the lamp 35 to ground. Relay 36, in operating, establishes a locking circuit for itself from battery through the contact of relay 9, normal contact of listening key 13, winding of relay 36, lower alternate contact thereof, and the winding of relay lOto ground. As soon as the subscriber quits turning the crank of the generator '39, relay 37 releases its armature, thereby permitting the operation of relay 40, which, however, at this time, performs no useful function. Upon the release of the armature of relay 37, the lamp 35 is intermittently lighted over a circuit from battery through the interrupter '38, upper alternate contact of relay 36, normal'coi'l- 13. Relay 14, in opertact of relay 137, and the lamp 35 to ground,

to furnish a disconnect signal. The operator, in removing theplugs from the jacks in response to the disconnect signals, re stores all apparatus to normal position.

Assuming, however, that, before the plugs are withdrawn from the jacks, subscriberA removes the receiver from the switchhook to initiate another call, The removal of the receiver from the switchhook by subscriber A causes the energization of answering supervisory relay 11 which causes the intermittent lighting of. the answering supervisory lamp 15 over a circuit from battery fhroughinterrupter 4L1, alternate contact of supervisory relay 1 1, alternate contact of relay 11, and lamp 15 to ground. The number of interruptions for a given length of time produced by interrupter 41 is different from that produced by interrupter 38, so that the intermittent lighting of the supervisory lamp 15 upon a recall is at a different rate than when intermittently lighted as a disconnect signal. The operator, in response to the recall indication of the answering supervisory lamp 15, may actuate listening key 13 to connect the telephone set to the cord circuit. In actuating the listening key 13, the normal contact thereof is opened, thereby releasing relays 12 and 14 and etfacing the supervisory lamp 15. The connection may now be completed in the manner heretofore described.

In the answering end of the cord circuit C, a ringing key 45 is provided which may be actuated to signal the subscriber of a, magneto line if that end of the cord circuit be connected with a line of this character. A relay 4:6. energized upon the actuation of the ringing key 45, is locked up under control of the listening key 13 and causes the lamp 15 to be lighted until the listening key 13 is actuated.

If the subscriber A had desired to be connected with a common battery line, the insertion of the calling plug 16 into the jack of the common battery line would cause the operation of relay 18 of the cord circuit and the cutoff relay of the line. The operation of relay 18 connects battery through the windings of the supervisory relay 37 to the cord circuit. Upon the operation of relay 18, the calling supervisory lamp 35 is lighted over a circuit from battery through the lower alternate contacts of relay 18, upper normal contact of relay 36, normal contact of calling supervisory relay 37, and calling lamp 35 to ground. Upon the response of the called subscriber, supervisory relay 37 operates to efface the supervisory lamp 35'. Also, upon response of this relay 37, relay 36. is operated. Relays 36 v and tO in the calling end'of the cord circuit C are similar respectively to relays 12 and 1% in the answering end, and function in the same manner.

It is thought'that the above description makes the operation of this system entirely clear, and that a further description of the operation in connection with the establishment of a connection between two magneto lines. is unnecessary.

What is claimed is:

1. A telephone exchange system comprising magneto and common battery telephone lines terminating at a central office, a universal link circuit for interconnecting the telephone lines, a signaling device in the link circuit, an interrupter, a relay in the link circuit controlled over a connected line,

either common battery or magneto, to include the interrupter in circuit with the signaling device to cause the signaling device to furnish a disconnect signal, a second interrupter, and relay mechanism serving when the receiver of a connected common battery line is subsequently removed from the switchhook to include the second interrupter in circuit with the signaling device to cause the intermittent operation thereof to furnish a recall signal.

2. A telephone exchange system compris ing a telephone line, a link circuit connected therewith, asource of ringing current, a signaling device, a switch for connecting the source of ringing current to the line, a relay energized upon the actuation of the switch to operate the signaling device, an operators telephone set, and a listening switch for connecting the operators telephone set to the link circuit and when actuated causing the deenergization of the relay.

3. A. telephone exchange system comprising a telephone line, a link circuit connected therewith, a source of ringing current, a switch for connecting the source of ringing current to the line, a signaling crevice operated upon the actuation of the switch, an operators telephone set, and a listening key actuated to connect the operators telephone set to the link circuit and stop the operation of the signaling device.

4. A telephone exchange system. comprising a telephone line. a source of ringing cuiy rent. a ringing key for connecting the source of ringing current to the line, a relay energized upon the actuation of the ringing key, a signaling device operating upon the energizat-ion of the relay. an operators telephone set, and a listening key actuated to connect the operators telephone set with the line and to de'e'nergize the relay thereby stopping the operation of the signaling device.

5. A telephone eXchano-e system comprising a telephone line, a cord circuit connected with the line, a source of ringing current, a-

ringing key in the cord circuit for connecting the source of ringing current to the line,

an operators telephone set, a listening key for connecting the operators telephone set to the cord circuit, a relay energized upon the actuation of the ringing key, a locking circuit for the relay established upon its energization and including a contact of the listening key, a signaling device, and an operating circuit for the signaling device established upon the energization of the relay nd including the before mentioned contact of the listening key and a contact of the relay.

6. A telephone exchange system comprising a cord circuit, two telephone lines connected together thereby, a source of ringing current, a ringing key associated with each end of the cord circuit for connecting the source :of ringing current to the respective connected lines, an operators telephone set-,a listening key :for connecting the 'operators telephone set with the cord circuit, a relay for each end "of the cord circuit energized upon the actuation of the corresponding ringing key, a locking circuit for each relay established upon the energization thereof, a signaling device controlled by each relay, and an operating circuit for veach signaling device established upon the energiz'ation of the controlling relay and including a contact of the listening key.

7. A telephone exchange system comprising magneto and common battery telephone lines terminating at a central office, a universa-l link circuit for interconnecting the telephone lines, a signaling device in the link circuit, a relay in the link circuit controlled over a connected line, either magneto or common battery, to establish an operating circuit for the signaling device to, furnish a disconnect signal, a second relay in the link circuit energized upon the energization of the first relay over a connected common loattery line, a third relay energized upon the deenergization of the first relay While the second is energized, interrupter mechanism, and an operating circuit for the signaling device and the interrupter mechanism completed upon the subsequent energization of the first relay While the second and third are energized.

8. A telephone exchange system comprising magneto and common battery telephone lines terminating at -a central oflice, a universal link circuit for interconnecting the telephone lines, a signaling device in the link circuit, a relay in the link circuit controlled over a connected .line, either magneto or common battery, to establish an operating circuit for the signaling device to furnish .a disconnect signal, ,a second relay in the link circuit energized upon the energization of the first relay over a connected common buttery line, athird relay energized upon the deenergization of the first relay While the second is energized, interrupter mechanism, and an operating circuit for the signaling device and the interrupter mechanism .completed upon the subsequent energization of the first relay and including contacts of the first and third relays. V

9. A telephone exchange system comprising magneto and common battery telephone lines terminating at a central 'oiiice, a uni versal link circuit for interconnecting :the telephone lines, a signal'i'ngdevice in the link circuit, a relay in the link circuit controlled over a connected line,.either magneto or common battery, to establish an operating {circuit forthe signaling device to tur-nish'a disconnect signal, a second relay in the link circuit energized upon the energi za-t-ion of the first relay, ;a third relay, an energizing circuit therefor including the second relay and completed upon the deener-gizati'on of the first relay, interrupter mechanism, and an operating circuit for the signaling device and the interrupter mechanism completed upon the subsequent cnergi'zation of the first relay while the secondand third are energized to furnish a recall signal from a connected common battery line.

10. A telephone exchange system compris ing magneto and common battery telephone lines terminatingat a central office, a un1versal link circuit for interconnecting the telephone lines. a signaling device in the link circuit, .a relay in the link circuit controlled over a connected line. either magneto or common battery, to establish an one-rating circuit for the signaling device including a contactof the relay to cause the operation of the signaling device to furnish a disconnect signal, a second relay in the link circuit, an energizing circuit therefor completed upon the energizationo'f the first relay and including a contact thereof and the signaling device, a third rel-ayenergized upon the delinergization of the first relay while the second is energized, interrupter mechanism, and an operating circuit for the signaling device and the interrupter mechanism completed upon the subsequent energization of the first relay While the second and third are energized to. l. v

furnish a recall-signal from a connected common battery line. 7 I I In Witness whereof, I .lrercunto subscribe my name this 23rd day of May, A. D. 1917 LEWIS JOHNSON.

Copies .0! this patent may be obtained tor fiye cents each. by adtiressing the Commissioner or Iatents, Washington, J). '0." 

